Geosynchronous Satellite Launch Vehicle (GSLV)

The Geosynchronous Satellite Launch Vehicle was primarily developed to launch INSAT class of satellites into Geosynchronous Transfer Orbits.

It is a launch vehicle system operated by the Indian Space Research Organization. It was developed to enable India to launch its satellites without dependence on foreign rockets and providers.

GSLV is now being used for launching GSAT series of satellites

GSLV is a three stage launcher that uses

Solid rocket motor stage

Earth storable liquid stage and

Cryogenic stage.

The first two stages were developed indigenously by ISRO and were being used in PSLV. India has been using cryogenic engines imported from Russia till recently. In august 2015 ISRO launched 2117 kg GSAT-6 using GSLV-D6. GSLV-D6 used indigenous cryogenic engine. ISRO's next target is to GSLV Mk3 which will be able to launch satellites weight 4 tonnes into the orbit.

In terms of weight, cryogenic fuel weighs 50% less than other propellant fuels. The lower weight of the cryogenic propellants makes it possible to carry additional payloads to longer distance.This makes launching heavy satellites into the space possible.

However, the handling of fuel and oxidizer at such low temperatures calls for highly complex and advanced technology as the fuels and oxidizer are extremely volatile.

Only recently ISRO has been successful in in developing indigenous cryogenic engines. ISRO launched 2117 kg GSAT-6 using GSLV-D6 which used indigenous cryogenic engine.

ISRO is working on developing cryogenic engines which can carry higher payloads (4000kg)

Importance

Cryogenic engines is a critical requirement for the success of India’s GSLV programme as it seeks to place about 2500-3000 kg communication geo-synchronous satellites in 36000 km high geo-stationary orbit.

The cryogenics are also essential requirements for the manned space flight ISRO’s is planning to launch in the near future. The lower weight of the cryogenic propellants makes it possible to carry additional payloads to longer distance.

Only the US, Russia, China, France and Japan have had this technology so far.

The early successful flights of GSLV used Russian-made cryogenic engines. ISRO’s initial attempts to use its own cryogenic engine in the GSLV resulted in failure. It was only in January last year that the first GSLV with an indigenous cryogenic stage engine made a successful flight.